Correlation of serum adipsin with pancreatic β cell function and insulin resistance in people with varying degree of glucose tolerance

Abstract

Objective To investigate the serum adipsin concentrations in people with different glucose tolerance and analyze its correlation with pancreatic β cell function as well as insulin resistance. Methods Based on the patient population who visited endocrinology deptartment or conducted health check in the First Afflicated Hospital of Chongqing Medical University from December 2015 to October 2016, 56 patients with newly diagnosed type 2 diabetes mellitus (T2DM group), 36 patients with impaired glucose regulation (IGR group), and 45 subjects with normal glucose tolerance (NGT group) were included. All subjects underwent intravenous glucose tolerance test (IVGTT). Acute insulin response (AIR), the area under the curve (AUC) of 0-10 min insulin secretion, homeostasis model assessments of insulin resistance index (HOMA-IR) and β-cell function index (HOMA-β) were calculated. Serum adipsin and interleukin-1β (IL-1β) were assayed by enzyme linked immunosorbent assay. The relationship between adipsin, AIR, AUC, HOMA-β, HOMA-IR and other metabolic parameters were analyzed. One-way analysis of variance(ANOVA) or nonparametric test were used for groups' comparisons. Pearson correlation analysis was used to determine simple bivariate relationships. Stepwise multiple regression analysis was conducted for adipsin as a dependent variable, including all variables of interest at the same time as independent variables. Results The levels of serum adipsin in T2DM group and IGR group were significantly decreased [3 201 (2 542-4 070), 5 159 (2 775-6 501) vs 6 833 (5 587-10 126) μg/L, H=24.372, P<0.05]. Serum adipsin levels were negatively correlated with WHR, FFA, FPG, 2hPG, HbA1c, HOMA-IR, IL-1β, hs-CRP (r=-0.521--0.285, all P<0.05), and were positively correlated with HOMA-β, HDL-C, AUC, AIR (r=0.325-0.577, all P<0.05). Multiple stepwise regression analysis showed that HOMA-β and AIR were independently associated with adipsin (βHOMA-β=0.332, P=0.038; βAIR=0.349, P=0.029). Conclusions Serum adipsin concentrations are decreased in T2DM and IGR, and are closely correlated with first-phase insulin secretion. Adipsin might involve in the development of type 2 diabetes mellitus. Key words: Diabetes mellitus, type 2; Adipsin; First-phase insulin secretion; Pancreatic βcell function; Insulin resistance